1. Field of the Invention
This invention relates generally to power-driven wrenches and has for a general object the provision of an improved power wrench that will enable the operator to turn a wide variety of sizes of bolt-heads or nuts when the work clearance is minimal. More particularly, this invention relates to power-driven wrenches in which the work-engaging tool and its housing are easily replaced, thus enabling the operator to select a tool that fits the work piece without the necessity of using a socket, thereby minimizing the work clearance necessary for use of the power wrench.
2. Description of the Prior Art
Both manual and power-operated gear-driven wrenches are well known. Typically, such wrenches comprise a ring gear that is adapted to receive sockets of varying sizes, and a drive shaft which engages the ring gear through a drive gear, all of which are journalled for rotation within a rigid housing. Manually operated wrenches of this type are exemplified by U.S. Pat. Nos. 2,764,048 and 3,630,106. A major disadvantage of such manually operated wrenches is the fact that rotation of the drive shaft applies both a desirable rotational force to the work piece and an undesirable force which is roughly perpendicular to its axis of rotation. In extreme cases, this can lead to damage to threads or even bending of a bolt.
The operator of a power-operated wrench in which the tool housing is integral with or firmly attached to the motor case can compensate for such undesirable force simply by manually applying a force to the motor case counter to the direction of rotation of the motor. Exemplary of such power-operated wrenches are U.S. Pat. Nos. 2,618,187 and 2,693,728. These power-operated wrenches also have a major disadvantage in the inability of a single such wrench to handle work pieces of varying size where the work clearance is small. Whenever a work piece is smaller than the orifice of the ring gear, it is necessary to employ compensating socket inserts in the orifice. When using such socket-fitted power wrench, it is essential that the clearance around small work pieces be greater than that around large ones. Such large clearances often are not available and a variety of complete power wrenches, of varying sizes is necessary.